The present invention relates to the lubricant grease compositions, in particular to the compositions for the treatment of friction pairs, and can be used in the machine building for the treatment of friction units, and also during the exploitation of different mechanisms and machines for prolongation of interrepair time or for damage control (repair-restore operations).
It is known that the task of any lubricant grease is to prevent direct contact between the surfaces and, consequently, its local welding with the aim to decrease power inputs for destruction of xe2x80x9cwelding bridgesxe2x80x9d and to decrease wear taking place in the points of surface contacts of friction pairs.
At the absence of direct contact between rubbing metals friction force is defined by resistance of displacement of lubricant, true contact area and loading. Consequently, friction can be principally decreased by the correct lubricant selection.
It is known that there are solid lubricants [Klamann D. Lubricants and Related Products. M.: Khimiya, 1988, pp. 164-176] on the basis of graphite, molybdenum disulphide and the series of oxides providing the decrease of shear resistance as they have flaky structure, which provides formation of the so called xe2x80x9cmirrors of slidingxe2x80x9d. They are used rather successfully simultaneously with mineral oils for the series of mechanisms and machines, and can be useful for providing xe2x80x9crepair lubricationxe2x80x9d for some time. However, it is not recommended to introduce solid lubricant in lubricating oil for severe conditions, as these oils consist of optimally balanced package of doped oil and solid lubricants can decrease these properties. Moreover, dispersion instability of solid greases leads to clogging of the oil circulation system, to xe2x80x9coil starvingxe2x80x9d and to jamming of metal details. It is necessary to note that the use of the mentioned solid greases does not provide the decrease of the friction coefficient below 0,01.
It is known that abrasive-like powder prepared out of natural serpentinite consisting of (in mass %) MgO, CaO-20-60, SiO2, Al2O3-20-60, H2O-3-10 and rock admixtures in quantity 3-10 [patent RU No.2006707, IC F 16 C 33/14, of 03.07.92] can be used as solid admixture. While using the powder it is suggest to make its mechanical activation at temperature 40-60xc2x0 C.
The use of natural pyrophyllite as antiwear additive to lubricant grease [patent RU No. 1377284, IC C 10 M 125/26, of 20.02.86] is also known.
It is supposed that abrasive-like powders of the mentioned compositions are able to increase wear resistance of rubbing surfaces.
However, as practice shows, the use of the powders of the mentioned compositions in series of cases does not give a desirable result and leads to quite opposite effect; it increases wear of friction pair surfaces.
The use of a mixture of minerals containing (in mass %) SiO-30-40, MgO-20-35, Fe2O3-10-15, FeO-4-6, Al2O3-3-8, S-2-6, accompanying admixtures-5-30 is also known (patent RU No. 2,057,257, filed Mar. 21, 1994). As it is said in the patent, the initial treatment takes place at a temperature not less than 300xc2x0 C. in a micro volume. It is the authors"" opinion that the mixture of natural minerals such as serpentine, enstatite, magnetite, talc, ilmenite, amphibole, brimstone, biotite and petlantide in the form of a powder with particle size 0.01-1.0 mxcexc is the basis for the oxide composition described in the patent. As a result of the use of the aforementioned minerals in different proportions, depending on the natural source, the formation of ultra strong surfaces and decreased wear is observed on some friction pairs. The authors noted that it is possible to use a machine without lubricant grease in xe2x80x9ctesting unitsxe2x80x9d for a long time.
The mixture of such a composition containing serpentine, talc, sulfur, pyrrotine, enstatite and fayalite is described in another patent (RU No. 2,035,636, filed Jul. 7, 1993). According to this description, the mixture was treated with dry saturated steam at a temperature of 110-115xc2x0 C. before use in order to deprive of water and stabilize the dispersion. Such a method of treatment, in the authors"" opinion, caused a decrease in the friction coefficient and stabilized the powder dispersion. The absence of figures in the invention description concerning dispersion, friction coefficient and other data gives evidence that the results obtained are not stable.
Moreover, concentrated lubricant product containing a mixture of hydroxides of nickel, zinc, copper, chromium in the proportion 1:1:1:1 based on the metal content, oleic acid and grease material is known (patent RU No. 2,016,050, filed Mar. 2, 1992). As is noted in the description, the use of the concentrated product reduces the grinding time in friction pairs and decreases wear 1.5-2 times.
However, the received results cannot be considered sufficient as the friction coefficient remains high (not lower than 0,061 and the use of oleic acid is a cause of corrosion phenomenon in friction pairs.
Patent RU No. 2,059,121 describes a composition for the treatment of friction pairs which comprises dehydrated powder containing (in mass %) MgO-39, SiO2-36, FeO, Fe2O2, Fe3O4-10, Al2O3, rare-earth metals-1.3, oxides Mn, Ni, Co, Cu, Ti, Zr, Cr-3.5 and other admixturesxe2x80x94the rest. Any raw material containing natural serpentinite deposits can provide such a composition. The use of the above-mentioned powder mixture gave a 3% increase in efficiency and 7% decrease of reducer temperature, although no other advantages of the mixture and methods of its use were described.
Also, it should be noted that while different serpentinite compositions prepared as a finely dispersed powder undoubtedly can affect wear resistance of friction pairs, this effect is evidently not stable. In a number of cases the result obtained is quite opposite. Wear resistance not only increases but wear is noticeable, not only initially when it can increase 5-6xc3x97 compared with the usual grinding effect. In addition, a decrease of friction coefficient does not occur.
The invention embodied in the present application provides an improved lubricating composition that reproducibly increases the wear resistance, reduces the friction coefficient and improves the operating characteristics of machines and equipment and their costs of operation.
The problem presented is solved according to the present invention by providing a defined stable composition for the treatment of friction pairs, which comprises metal and non-metal oxides.